Technical Presentations

Single Pole Auto Reclosure and NGR Analysis 794

Abstract
Unsuccessful auto reclosure has been observed in 765 kV HVAC transmission lines connected with Generation Bus. Back up Impedance Protection of Line reactor triggered during AR dead time due to power f... see morerequency oscillations in faulty phase (disconnected phase). It triggered tripping of Non Switchable Line Reactor at one end, which resulted tripping of 765 kV HVAC Line and avoidable Generation loss.

These Unsuccessful AR operations triggered us to study and model entire phenomena in Power System Analysis software (EMTP).


Initially, two circuits of 765 kV Transmission Line commissioned between Generation Station and Transmission Station with Line Reactor and NGR in both line at either end. Successful auto reclosure observed during single-phase faults on these lines. Intermediate Switching station constructed and both lines were divided in 4 section as per new requirement. Same configuration (rating) of Line Reactor and NGR adopted at newly constructed station on each line. Unsuccessful AR observed during AR running cycle on these lines after new configuration. Backup Impedance protection of Line Reactor found operated during AR Dead time.
Different sets of simulations has been carried out to understand the phenomena:

- Single Phase fault and Auto reclosure in 765 kV Transmission line in different section of entire corridor with Varying Shunt compensation (Value of Line Reactor)
- Different NGR values and observations for above simulations
- Trip the Line Reactor Breaker during Auto Reclosure Phenomena to avoid operation of Backup Impedance protection and its consequences

After EMTP Simulations and study, it was concluded that:

- Line Reactor (Degree of compensation) should be adjusted with adequate value while line length altered from its original design.
- NGR re-sizing can address the issues at some extent. Suitable value of NGR (based on Line Length and amount of shunt compensation) should be employed
Appropriate Solution and mitigation suggested after detail simulation & study.

Tag(s): single pole, analysis, auto reclosure, line reactor

TOV for renewable, evaluating three different grounding technologies783

Abstract
Temporary overvoltages (TOV) are oscillatory overvoltages mainly caused by switching or faults, which are of relatively long duration and undamped or slightly damped. Maximum overvoltages under faulte... see mored conditions can require considerable energy magnitudes absorbed by surge arresters.
These energies may overpass maximum limits and lead to equipment damage.

This project presented a study to identify the maximum TOV at the MV equipment of a PV power plant during fault-clearing events. Two methods of TOV suppression are evaluated, including grounding transformers and fast grounding switches under two different configuraions. An electrical model was elaborated in EMTP to perform the simulation of the transient overvoltage due to the un-balanced fault clearance, considering each inverter of the PV plant. The results show that considering no grounding technologies at the feeders, the energy absorption limit is overpassed in the islanded system.

Therefore, a fast grounding switch or a system with grounding technology at each feeder is needed in order to protect the substation equipment.

Induced Currents and Voltages in Underground Metallic Pipelines due to nearby Power Lines782

Abstract
During the last decades, environmental and economic reasons impose that gas or water pipelines share the same distribution paths with high voltage or medium voltage power lines, to restrain the financ... see moreial and the ecological costs. Therefore, the cases where underground metallic pipelines and power lines share proximal rights-of way for considerable lengths are a common practice.
The electromagnetic interference of power lines upon the metallic buried pipelines is an issue of priority, to avoid the development of induced voltages that could jeopardize the safety of the personnel and the integrity of the pipelines structure. Indeed, the developed voltages and currents can be dangerous for people who touch metallic structures connected with the pipelines or just stand nearby.

Moreover, the induced voltages can result in the corrosion of a pipeline due to electrochemical effect, leading to repair or/and replacement costs and environmental repercussions.

It is worth mentioning that the interference comprises an inductive, a conductive and a capacitive part. The capacitive part can be safely ignored in the case of buried pipelines, since the conductive component is considered only under fault conditions and affects the part of the pipeline near the faulted structure.

The inductive component is present both during faults and normal operating conditions and is the dominant one. Due to the inductive interference, voltages and currents are induced in a buried metallic pipeline.

Transient immunity assessment of wind and solar parks773

Abstract
Abstract
Inverter-base Resources (IBRs), such as solar photovoltaic (PV) and wind parks are subject to transients which may cause more issues as compare to traditional generation due to the colle... see morector grid and the geographical spread between converters. In this webinar, we present several challenges which may be faced by planners and park developers:
- Transient immunity against utility-owned capacitor bank switching. Assessment of IEEE Std 1547-2018.
- Ferroresonance after open-phase faults.
- Temporary overvoltage (TOV) in a PV parks after a phase-to-ground fault
Events and EMTP simulations will be described and analysed during the webinar.
This work was performed with the collaboration of Bob Arritt, EPRI and Chest Li, Hydro One

Presenters:
• Hossein Ashourian - Power System Modeling and Simulation Specialist

• Anton Stepanov - Research And Development Specialist

Performance of conventional sources vs Inverter based source during power system faults771

Abstract
This presentation will contract the performance of conventional power source to those of inverter based resources (IBR) and how this impacts the performance of traditional protection devices.